public void CalculatePlanetApparentPlaceLP()
{
double jde = 2448976.5;
double tau = 0;
CrdsEcliptical ecl = null;
for (int i = 0; i < 2; i++)
{
CrdsHeliocentrical hEarth = PlanetPositions.GetPlanetCoordinates(3, jde - tau, highPrecision: false);
CrdsHeliocentrical hVenus = PlanetPositions.GetPlanetCoordinates(2, jde - tau, highPrecision: false);
var rect = hVenus.ToRectangular(hEarth);
ecl = rect.ToEcliptical();
tau = PlanetPositions.LightTimeEffect(ecl.Distance);
}
// Correction for FK5 system
CrdsEcliptical corr = PlanetPositions.CorrectionForFK5(jde, ecl);
ecl += corr;
ecl += Nutation.NutationEffect(16.749 / 3600.0);
CrdsEquatorial eq = ecl.ToEquatorial(23.439669);
Assert.AreEqual(new HMS("21h 04m 41.459s"), new HMS(eq.Alpha));
Assert.AreEqual(new DMS("-18* 53' 16.66''"), new DMS(eq.Delta));
}
/// <summary>
/// Gets heliocentrical coordinates of planet
/// </summary>
private CrdsHeliocentrical Planet_Heliocentrical(SkyContext c, int p)
{
// final difference to stop iteration process, 1 second of time
double deltaTau = TimeSpan.FromSeconds(1).TotalDays;
// time taken by the light to reach the Earth
double tau = 0;
// previous value of tau to calculate the difference
double tau0 = 1;
// Heliocentrical coordinates of planet
CrdsHeliocentrical planetHeliocentrial = null;
// Heliocentrical coordinates of Earth
CrdsHeliocentrical hEarth = c.Get(Earth_Heliocentrial);
// Iterative process to find heliocentrical coordinates of planet
while (Math.Abs(tau - tau0) > deltaTau)
{
// Heliocentrical coordinates of planet
planetHeliocentrial = PlanetPositions.GetPlanetCoordinates(p, c.JulianDay - tau, !c.PreferFastCalculation);
// Ecliptical coordinates of planet
var planetEcliptical = planetHeliocentrial.ToRectangular(hEarth).ToEcliptical();
tau0 = tau;
tau = PlanetPositions.LightTimeEffect(planetEcliptical.Distance);
}
return(planetHeliocentrial);
}
public void CalculatePlanetApparentPlaceHP()
{
double jde = 2448976.5;
// time taken by the light to reach the Earth
double tau = 0;
// previous value of tau to calculate the difference
double tau0 = 1;
// final difference to stop iteration process, 1 second of time
double deltaTau = TimeSpan.FromSeconds(1).TotalDays;
// Ecliptical coordinates of Venus
CrdsEcliptical ecl = null;
// Iterative process to find ecliptical coordinates of Venus
while (Math.Abs(tau - tau0) > deltaTau)
{
// Heliocentrical coordinates of Earth
var hEarth = PlanetPositions.GetPlanetCoordinates(3, jde - tau, highPrecision: true);
// Heliocentrical coordinates of Venus
var hVenus = PlanetPositions.GetPlanetCoordinates(2, jde - tau, highPrecision: true);
// Ecliptical coordinates of Venus
ecl = hVenus.ToRectangular(hEarth).ToEcliptical();
tau0 = tau;
tau = PlanetPositions.LightTimeEffect(ecl.Distance);
}
// Correction for FK5 system
ecl += PlanetPositions.CorrectionForFK5(jde, ecl);
// Take nutation into account
ecl += Nutation.NutationEffect(16.749 / 3600.0);
// Apparent equatorial coordinates of Venus
CrdsEquatorial eq = ecl.ToEquatorial(23.439669);
Assert.AreEqual(new HMS("21h 04m 41.454s"), new HMS(eq.Alpha));
Assert.AreEqual(new DMS("-18* 53' 16.84''"), new DMS(eq.Delta));
}
/// <summary>
/// Gets rectangular heliocentric coordinates of minor body
/// </summary>
protected CrdsRectangular RectangularH(SkyContext c, T body)
{
// final difference to stop iteration process, 1 second of time
double deltaTau = TimeSpan.FromSeconds(1).TotalDays;
// time taken by the light to reach the Earth
double tau = 0;
// previous value of tau to calculate the difference
double tau0 = 1;
// Rectangular coordinates of minor body
CrdsRectangular rect = null;
// Rectangular coordinates of the Sun
var sun = c.Get(SunRectangular);
// Orbital elements
var orbit = c.Get(OrbitalElements, body);
double ksi = 0, eta = 0, zeta = 0, Delta = 0;
int count = 0;
// Iterative process to find rectangular coordinates of minor body
while (Math.Abs(tau - tau0) > deltaTau && count++ < 100)
{
// Rectangular coordinates of minor body
rect = MinorBodyPositions.GetRectangularCoordinates(orbit, c.JulianDay - tau, c.Epsilon);
ksi = sun.X + rect.X;
eta = sun.Y + rect.Y;
zeta = sun.Z + rect.Z;
// Distance to the Earth
Delta = Math.Sqrt(ksi * ksi + eta * eta + zeta * zeta);
tau0 = tau;
tau = PlanetPositions.LightTimeEffect(Delta);
}
return(rect);
}
/// <summary>
/// Calculates heliocentrical coordinates of Pluto for J2000 epoch
/// </summary>
private CrdsHeliocentrical Pluto_HeliocentricalJ2000(SkyContext c)
{
// final difference to stop iteration process, 1 second of time
double deltaTau = TimeSpan.FromSeconds(1).TotalDays;
// time taken by the light to reach the Earth
double tau = 0;
// previous value of tau to calculate the difference
double tau0 = 1;
// Sun rectangular coordinates, J2000.0 epoch
CrdsRectangular rSun = c.Get(Sun_RectangularJ2000);
// Heliocentrical coordinates of Pluto
CrdsHeliocentrical plutoHeliocentrial = null;
// Iterative process to find heliocentrical coordinates of planet
while (Math.Abs(tau - tau0) > deltaTau)
{
// Heliocentrical coordinates of Pluto
plutoHeliocentrial = PlutoPosition.Position(c.JulianDay - tau);
// Rectangular heliocentrical coordinates of Pluto
CrdsRectangular rPluto = new CrdsEcliptical(plutoHeliocentrial.L, plutoHeliocentrial.B, plutoHeliocentrial.R).ToRectangular(epsilonJ2000);
double x = rPluto.X + rSun.X;
double y = rPluto.Y + rSun.Y;
double z = rPluto.Z + rSun.Z;
double dist = Math.Sqrt(x * x + y * y + z * z);
tau0 = tau;
tau = PlanetPositions.LightTimeEffect(dist);
}
return(plutoHeliocentrial);
}
private void DoTest(CrdsGeographical location, OrbitalElements oe, string testData, double errorR, double errorEq)
{
Regex regex = new Regex("^(\\S+)\\s+(\\S+)\\s+(\\S+)\\s+(\\S+)\\s+(\\S+ \\S+ \\S+) (\\S+ \\S+ \\S+)$");
string[] lines = testData.Split('\n');
foreach (string line in lines)
{
string dataLine = line.Trim();
if (!string.IsNullOrEmpty(dataLine))
{
var match = regex.Match(dataLine);
double jd = double.Parse(match.Groups[1].Value, CultureInfo.InvariantCulture);
double X = double.Parse(match.Groups[2].Value, CultureInfo.InvariantCulture);
double Y = double.Parse(match.Groups[3].Value, CultureInfo.InvariantCulture);
double Z = double.Parse(match.Groups[4].Value, CultureInfo.InvariantCulture);
string ra = match.Groups[5].Value;
string dec = match.Groups[6].Value;
var eqTest = new CrdsEquatorial(new HMS(ra), new DMS(dec));
var nutation = Nutation.NutationElements(jd);
var aberration = Aberration.AberrationElements(jd);
// True obliquity
double epsilon = Date.TrueObliquity(jd, nutation.deltaEpsilon);
// final difference to stop iteration process, 1 second of time
double deltaTau = TimeSpan.FromSeconds(1).TotalDays;
// time taken by the light to reach the Earth
double tau = 0;
// previous value of tau to calculate the difference
double tau0 = 1;
// Rectangular coordinates of minor body
CrdsRectangular r = null;
// Rectangular coordinates of the Sun
var sun = SunRectangular(jd, epsilon);
// Distance to the Earth
double Delta = 0;
// Iterative process to find rectangular coordinates of minor body
while (Math.Abs(tau - tau0) > deltaTau)
{
// Rectangular coordinates of minor body
r = MinorBodyPositions.GetRectangularCoordinates(oe, jd - tau, epsilon);
double ksi = sun.X + r.X;
double eta = sun.Y + r.Y;
double zeta = sun.Z + r.Z;
// Distance to the Earth
Delta = Math.Sqrt(ksi * ksi + eta * eta + zeta * zeta);
tau0 = tau;
tau = PlanetPositions.LightTimeEffect(Delta);
}
// Test heliocentric rectangular coordinates
Assert.AreEqual(X, r.X, errorR);
Assert.AreEqual(Y, r.Y, errorR);
Assert.AreEqual(Z, r.Z, errorR);
double x = sun.X + r.X;
double y = sun.Y + r.Y;
double z = sun.Z + r.Z;
double alpha = Angle.ToDegrees(Math.Atan2(y, x));
double delta = Angle.ToDegrees(Math.Asin(z / Delta));
var eq0 = new CrdsEquatorial(alpha, delta);
var theta0 = Date.ApparentSiderealTime(jd, nutation.deltaPsi, epsilon);
var parallax = PlanetEphem.Parallax(Delta);
var eq = eq0.ToTopocentric(location, theta0, parallax);
// Test equatorial coordinates
Assert.AreEqual(eqTest.Alpha, eq.Alpha, errorEq / 3600.0);
Assert.AreEqual(eqTest.Delta, eq.Delta, errorEq / 3600.0);
}
}
}
public void Position()
{
// Mean obliquity of the ecliptic for J2000.0 epoch
const double epsilonJ2000 = 23.4392912510;
double jd = 2448908.5;
double tau = 0;
double tau0 = 1;
int iteration = 1;
// final difference to stop iteration process, 1 second of time
double deltaTau = TimeSpan.FromSeconds(1).TotalDays;
CrdsHeliocentrical posPluto = null;
CrdsHeliocentrical hEarth = null;
while (Math.Abs(tau - tau0) > deltaTau)
{
posPluto = PlutoPosition.Position(jd - tau);
if (iteration == 1)
{
Assert.AreEqual(232.74071, posPluto.L, 1e-5);
Assert.AreEqual(14.58782, posPluto.B, 1e-5);
Assert.AreEqual(29.711111, posPluto.R, 1e-6);
}
else if (iteration == 2)
{
Assert.AreEqual(232.73949, posPluto.L, 1e-5);
Assert.AreEqual(14.58801, posPluto.B, 1e-5);
Assert.AreEqual(29.711094, posPluto.R, 1e-6);
}
// get Earth coordinates
hEarth = PlanetPositions.GetPlanetCoordinates(3, jd, highPrecision: false, epochOfDate: false);
// transform to ecliptical coordinates of the Sun
CrdsEcliptical eclSun = new CrdsEcliptical(Angle.To360(hEarth.L + 180), -hEarth.B, hEarth.R);
CrdsRectangular rSun = eclSun.ToRectangular(epsilonJ2000);
if (iteration == 1)
{
Assert.AreEqual(-0.9373959, rSun.X, 1e-6);
Assert.AreEqual(-0.3131679, rSun.Y, 1e-6);
Assert.AreEqual(-0.1357792, rSun.Z, 1e-6);
}
var rPluto = new CrdsEcliptical(posPluto.L, posPluto.B, posPluto.R).ToRectangular(epsilonJ2000);
if (iteration == 1)
{
Assert.AreEqual(-17.4079141, rPluto.X, 1e-5);
Assert.AreEqual(-23.9730804, rPluto.Y, 1e-5);
Assert.AreEqual(-2.2374228, rPluto.Z, 1e-5);
}
else if (iteration == 2)
{
Assert.AreEqual(-17.4083780, rPluto.X, 1e-5);
Assert.AreEqual(-23.9727452, rPluto.Y, 1e-5);
Assert.AreEqual(-2.2371797, rPluto.Z, 1e-5);
}
double x = rPluto.X + rSun.X;
double y = rPluto.Y + rSun.Y;
double z = rPluto.Z + rSun.Z;
double dist = Math.Sqrt(x * x + y * y + z * z);
if (iteration == 1)
{
Assert.AreEqual(30.528746, dist, 1e-5);
}
else if (iteration == 2)
{
Assert.AreEqual(30.528739, dist, 1e-5);
}
tau0 = tau;
tau = PlanetPositions.LightTimeEffect(dist);
if (iteration == 1 || iteration == 2)
{
Assert.AreEqual(0.17632, tau, 1e-5);
}
iteration++;
}
// should be only 2 iterations
Assert.AreEqual(2, iteration - 1);
// ecliptical coordinates of Pluto, J2000.0 epoch
var eclPluto = posPluto.ToRectangular(hEarth).ToEcliptical();
// geocentric astrometric equatorial coordinates of Pluto, J2000.0 epoch
var eqPluto2000 = eclPluto.ToEquatorial(epsilonJ2000);
// check coordinates with possible error with 1 arcsecond
Assert.AreEqual(new HMS("15h 31m 43.8s").ToDecimalAngle(), eqPluto2000.Alpha, 1 / 3600.0);
Assert.AreEqual(new DMS("-4* 27' 29''").ToDecimalAngle(), eqPluto2000.Delta, 1 / 3600.0);
}
